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From David Hawthorne <dha...@gmx.3crowd.com>
Subject high level of MemtablePostFlusher pending events
Date Wed, 14 Mar 2012 02:45:47 GMT
5 node cluster running 1.0.2, doing about 1300 reads and 1300 writes/sec into 3 column families
in the same keyspace.  2 client machines, doing about the same amount of reads/writes, but
one has an average response time in the 4-40ms range and the other in the 200-800ms range.
 Both running identical software, homebrew with hector-1.0-3 client.

Traffic was peaking out at 6k reads and 6k writes/sec, according to reporting from our software,
and now it's topping out at 1300/sec each.  The cpus on the cassy boxes are bored.  None of
the threads within cassandra are chewing more than 3% cpu.  Disk is only 10% full on the most
loaded box.

MemtablePostFlusher               1       102             36

Not all servers have the same number of pending tasks.  They have 0, 1, 17, 37, and 105.

It looks like it's stuck and not recovering, cuz it's been like this for an hour.  I've attached
the end of the cassandra.log from the server with the most pending tasks.  There are some
interesting exceptions in there.

As always, all help is always appreciated!  :p



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